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Post #1
 16th June 2008 - 03:03 AM
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Basically, I'm at a loss to explain it. So hopefully some tech-heads on here can lend me some advice. The short relevant specs of the car related the Engine/Driveline are: - JDM Avenir PNW10 SR20DET (2L Turbo) conversion from stock GA16DE (1.6L Naturally Aspirated), custom wiring harness, retaining Air-con. - Avenir Auto ECU re-mapped by Dr Drift - Nismo 740cc injectors - Genuine Z32 Airflow Meter with Bosch plug - HKS EVC 6 Boost Controller - Two Aftermarket Auto Transmission Coolers - 600x300x76 Hybrid Copy Front Mount Intercooler, custom Stainless Steel piping - Go Fast Bits StealthFX BOV - Custom Aluminium Pod Box with 3A Racing Pod Filter, Metal Intake Pipe - GT28RS 'Disco Potato' .64 housing with modified actuator bracket and rod - Pulsar RNN14 GTiR Exhaust Manifold - Longer Manifold Studs - Liverpool Exhaust 10mm Manifold Spacer Plate - 3" full Stainless Steel mandrel bent Exhaust, Stainless Steel straight-though Muffler - CES Split GTi-R Dump Pipe - CES Metal Substrate Cat - Pulse PHB650 Dry Cell Battery - Pulsar N14 JDM SR18DE Auto Transmission with VLSD, rebuilt for turbo application completely from scratch; Custom Valve Body Custom Heavy Duty Clutch Packs and Hubs Custom Heavy Duty Band and Drum 12mm wider than standard Custom Torque Converter with Heavy Duty Lock Up Clutch and Roller Bearings Custom machined Servo Assembly SR18DE Sentra Shift Kit The car is a 1998 Nissan Pulsar LX Sedan. These are the most recent dyno sheets: On 17PSI:  13PSI (stock actuator boost) VS 17PSI:  Note: Peak power is almost identical, it gets to a certain point (160fwkw) and plateaus off. No matter how much boost you run, it makes the same peak power. Torque and low-down power increase...but then it goes flat... Wtf am I missing? The car has spark, fuel, boost. It's not running lean nor rich. Ignition timing has been backed off a smidge (2'.) The 13PSI reading was the untuned figure. The 17PSI reading is the tuned figure. It doesn't blow smoke, it doesn't misfire, it doesn't overheat, the Auto doesn't slip. What on earth could it be? -------------------- 1998 N15 Pulsar LX Sedan (SR20DET) – weekend warrior (196.2fwkw)
1998 R34 Skyline 25GT-T Sedan (RB25DET) - For Sale 2005 YGZ11 Cube Cubic 15M (HR15DE) - the new daily, all sorts of boxy awesome |
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mongrel_cae71
Post #3
funny how the torque/motive force changers, yet the power hits a wall just before 160kws. I wouldn't be to concered about the engine, I'd be more looking at the auto or if the you're doubly sure it's not the auto, then maybe it was starting to dance on the rollers. |
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iamhappy46
Post #6
To check if the auto is slipping under load, compare engine rpm(using the Mainline dyno injector pulse timing) to roller speed. It is obvious that from 130kph, the power curve should still be climbing. |
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llama_au
Post #7
QUOTE(mongrel_cae71 @ Jun 17 2008, 07:09 AM) [snapback]1282483177[/snapback] funny how the torque/motive force changers, yet the power hits a wall just before 160kws. I wouldn't be to concered about the engine, I'd be more looking at the auto or if the you're doubly sure it's not the auto, then maybe it was starting to dance on the rollers. if theire is a problem with the auto, you might not notice it. on the road it might feel fine, because you've probably never fully loaded 3rd and 4th gear all the way to the red. on the rollers you won't feel minor flares as you can't judge the acceleration of the car by 'seat-of the pant's' if that makes sence. It was wheel-spinning the dyno a tiny bit, but it's not that. We had three people sit on the radiator support. The car is with my Auto builder for a week, so he's got a week to get a feel for how it's driving. He refuses to believe the power is just being 'sucked up' by the Auto. It should make more power - not as much as a manual, but increasing boost should produce a gain of some sort. I can't gain a single kw no matter what boost is run. I'm trying to rule out the the engine as a cause first - I suspect cam timing could be well and truly out of whack. The timing chain was replaced roughly a year ago. I'm also going to drop the exhaust off to see if there's a restriction there, and take the cooler off to see if it's blocked. I don't believe either of those to be the issue but I want to rule them out before looking at the Auto. It's also running enough ignition timing up top, it can run more (it's retarded by 2' or it knocks...), the tune it good - the AFR's are good. I've got a lot to consider. Matt - the stall is standard 2500rpm. My Auto builder doesn't have a dyno, only my tuner does and they're nowhere near each other. My tuner's not qualified to diagnose the Auto, obviously my Auto builder is but he doesn't have a dyno. He has driven the car and said the Auto is functioning fine. It never flares on gear changes, gear changes are hard and precise, lock-up clutch on the torque converter engages and disengages instantly on 3rd-4th gear changes. The Auto functions great. My tuner isn't an expert but he also agrees there's no way the Auto is slipping, from how it drives and how it is on the dyno. |
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09ONE
Post #8
I was going to say check exhaust/intake tract for some kind of a restriction, but your already onto it. |
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GTRVspec95
Post #10
Westinghouse, |
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GTRVspec95
Post #12
QUOTE(llama_au @ Jun 17 2008, 03:21 PM) [snapback]1282485569[/snapback] It's not running out of fuel. I do plan to upgrade it if it's not keeping up...but it's fine. The car is getting enough fuel. Are you sure ... The Nismo 740's won't be running full duty cycle thats for sure, but doesn't mean that a stock pump will be able to feed the bigger injectors the amount of fuel they can pump out. I'd just check that out J as it's a very common wall for Silvia's with stock/old pumps to hit at that power range  |
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iamhappy46
Post #14
If it was leaning out, it would be leaning out when it hits around 130kph, so it would be having major problems all the way to the rev limiter. That rules out fueling. |
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09ONE
Post #15
QUOTE(GTRVspec95 @ Jun 17 2008, 04:06 PM) [snapback]1282485848[/snapback] Are you sure ... The Nismo 740's won't be running full duty cycle thats for sure, but doesn't mean that a stock pump will be able to feed the bigger injectors the amount of fuel they can pump out. I'd just check that out J as it's a very common wall for Silvia's with stock/old pumps to hit at that power range I had this problem in my old R32 with RB20 but it didn't suffer from the symptoms llama_au is experiencing. The engine was running lean with the injector duty maxed... Took off the return line to the tank and held it over a bucket and gave the car a boot on the dyno. As soon as it came onto full boost there was no fuel running out the return line so the engine was using every drop of fuel being supplied to the rail. |
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llama_au
Post #16
QUOTE(iamhappy46 @ Jun 17 2008, 07:06 PM) [snapback]1282487122[/snapback] If it was leaning out, it would be leaning out when it hits around 130kph, so it would be having major problems all the way to the rev limiter. That rules out fueling. Cam timing would cause idle issues and would alter the power curve much more than what you have here along with throwing out the boost response curve. How does it actually drive on the road(110+kph on a private road of course) because if it holds your head flat against the head rest through the whole rev range, it could just be a dyno anomaly and making more power than the dyno is registering. In this case, enjo the car as it is If it was peaking and then plateauing like that on the road, you have less driven torque so there would be no surge of torque/power above 130kph and you could pull your head off the headrest quite easily above these speeds. If that is the case, then I would be worrying. It keeps pulling past 200kmp/h at the drags and track...and in 3rd gear  I know dynos have trouble reading the power produced in Auto car...but I still would thought I'd see increases for each extra PSI. As you can see it has a higher peak torque but where does the power go? |
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HYBRID_AE86
Post #17
we have built a car in the past that has made around 470rwhp, tuned by Sam. we have had the same car tuned by someone else, and made 630rwhp. |
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llama_au
Post #18
Sam's at a loss to explain it. All the right ingredients are there and the car runs very well. Sam has tuned it on the safe side, but that's not the issue. |
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iamhappy46
Post #19
Alright, I am leaning towards the auto playing up on the dyno under load. If the torque output was like the dyno says it would be, then it would feel like your driving a diesel non-turbo hilux. Big surge of mid range torque but gutless up top. |
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iamhappy46
Post #20
Also, by measuring the injector pulse timing on the dyno(for rpm) the Mainline dyno can read the pulse width which should give your tuner an idea as to how much fuel is being added above 130kph. |
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llama_au
Post #22
The answer from Sam: QUOTE The Auto definitely didn't feel like it was slipping which was why I didn't lean towards it... And the injector pulse width will not lean towards ECU related problems as the fuel map is near perfect. The auto has been apart and inspected now. It's not slipping, so whatever it is not tune or auto related. |
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iamhappy46
Post #23
Injector pulse gives an idea of how much fuel is being injected. I can see that the tune is good BUT if the injector pulse is increasing in a linear rate to rpm from 130kph, then it would be running RICH to hover at that power level above 140kph. |
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iamhappy46
Post #25
Just going through the W10 ECU binary, I have a suspicious table(known as the maximum load table) that may be the problem. Comparing the W10 table, it has 10001000(136 in decimal) from 4800rpm to rev limiter but a auto S13 ECU has 11111111(255 in decimal) in the same spot. |
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llama_au
Post #27
Response from Sam: QUOTE Max Load = AFM Limit Table (most people commonly refer to as boost cut) I have removed the Max Load limit completely since the first tune. If you exceed the Max Load it cuts out, not reduces torque, and as the ignition is not being retarded, and the fuel is spot on, it can have nothing to do with that. I'm still certain it's flow related - An engine is just an air pump, something is at 160rwkw limit... I still think cams/cooler piping/exhaust |
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^sims^
Post #28
I didn't really read over the thread totally so I'm not sure if this has been check or if it's even relivant (sorry its a long thread and I don't have time atm |
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iamhappy46
Post #31
Thats the clincher then... cam gear timing is out. |
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iamhappy46
Post #33
If the cam timing is out, I would also be checking the tune is safe again as ignition timing and fuel tables may need some minor adjustments. |
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llama_au
Post #35
So, the good news. Compression test is really good. 158, 160, 158, 158. In comparison my brothers 10,000km rebuild made 132, 132, 138, 132. Needless to say he's not particularly happy. It'd suggest that my engine does have the genuine km's it was sold to me as having (under 50,000km, it'd now have around 70,000km on it at maximum.) I wouldn't have guessed it the first time I saw it with the rocker cover off covered in thick sludgey oil. So I'm extremely happy my compression is factory spec. |
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